1. Field of the Invention
The present invention relates to a filtering device for an espresso maker. In particular, the present invention relates to a filtering device for an espresso maker for providing improved flavor.
2. Description of the Related Art
A conventional espresso maker uses a high-pressure pump to force water into a heater at a pressure of 10 kg/cm2. The water is heated by the heater to about 94° C. The hot water enters a coffee powder basket 1′ (FIG. 6) that receives coffee powder 2′ (FIG. 7). The coffee powder basket 1′ includes dozens of meshes 11′ of a diameter smaller than 0.5 mm to provide a filtering function. The high-pressure and high-temperature water passing through the coffee powder basket 1′ dissolves the substances contained in the coffee powder, such as caffeine and coffee berry oil. Flavored espresso is obtained by adding a layer of coffee cream (or creamy layer) floating on the level of the coffee. The creamy layer is formed by means of mixing the coffee berry oil with air under high-speed turbulent. However, the holes 11′ are too large and thus cause a pressure drop, failing to obtain the speed and turbulence required for the coffee berry oil to encompass air for forming coffee foams.
FIG. 8 shows another conventional coffee powder basket 3′ and FIG. 9 shows operation of the coffee powder basket 3′ receiving coffee powders 2′. The coffee powder basket 3′ includes a plurality of meshes 31′ of a diameter smaller than 0.5 mm to provide a filtering function. Further, a hole 32′ of a diameter smaller than 0.5 mm is provided below the meshes 31′. By this arrangement, the internal pressure of the coffee powder basket 3′ can be kept at about 10 kg/cm2. The high-pressure and high-temperature water that dissolves the substances contained in the coffee powders exits the coffee powder basket 1′ via the hole 32′, providing more coffee foams. However, since the coffee is directly guided out of the coffee powder basket 3′ by the hole 32′ (FIG. 9), the space allowing mixing of the coffee and the air is limited. As a result, the coffee foam-forming effect is still unsatisfactory.